Chart reading mechanism



Dec. 4, 1962 1 s. WILLIAMS CHART READING MECHANISM Original Filed June24, 1957 6 Sheets-Sheet 1 INVENTOR. LAWRENCE S. WILLIAMS ATTORNEYS Dec.4, 1962 L. s. WILLIAMS cam READING MECHANISM Original Filed June 24,1957 6 Sheets-Sheet 2 INVENT OR.

LAWRENCE SWILLIAMS ATTORNEYS Dec. 4, 1962 s. WILLIAMS 3,066,860

CHART READING MECHANISM Original Filed June 24, 1957 6 Sheets-Sheet 3INVENTOR.

LAWREI XCE S. WILLIAMS U U SHE [I Ff Dec. 4, 1962 L. s. WILLIAMS3,066,860 CHART READING MECHANISM Original Filed June 24, 1957 6Sheets-Sheet 4 IXU DIX U U H5 HHHHHUHHXHHF INVENTOR.

LAWRLZYNCE s. WILLIAMS Big. I

ATTORNEYS Dec. 4, 1962 L. s. WILLIAMS 3,066,860

CHART READING MECHANISM Original Filed June 24, 1957 6 Sheets-Sheet 5INVENTOR.

LAWBENCE S WILLIAMS ATTORNEYS Dec. 4, 1962 L. s. WILLIAMS 3,066,860

CHART READING MECHANISM Original Filed June 24, 1957 6 Sheets-Sheet 6lie- INVENT OR.

LAWIEQYENCE s. WILLIAMS ATTORNEYS Unite 3,056,860 Patented Dec. 4, 19626 Claims. (Cl. 23s 1 This invention relates to mechanical chart readingdevices.

As industrial processes and inventory control using condition responsiveinstruments become more and more exact there is a need for acorresponding increase in the accuracy of reading and recording theindications of the instruments. While the reading device constructedaccording to the invention may be applied to various types of conditionresponsive mechanism it is, for illustrative purposes only, described inconnection with its use in a weighing scale for reading the graduationsof a chart that moves according to the weight of a load being weighedand setting mechanism for visual display or printing of weightindications in digital form. The accuracy of a digital indication islimited only by the number of places into which the recording may beresolved. In order to get high accuracy it is necessary to graduate thechart with finely spaced graduations and the difiiculty of reading,particularly by mechanical means, is thereby materially increased.

The basic chart reading device with which the invention is concerned isdisclosed in abandoned application Serial No. 616,517 filed on October17, 1956, the present application being a continuation of abandonedapplication Serial No. 667,595 filed on June 24, 1957 which is acontinuation-impart of such application Serial No. 616,517, and includesa permutation disk assembly having a plurality of disks for each orderin the result which disks are set by momentary contact with relativelyraised and depressed surfaces of a chart and are arranged to be sensedby and control the movement of a member the travel of which correspondsto the digital value of the graduation being sensed.

The present invention provides a flexible annular chart of nonplane formhaving a front portion carrying raised indicia and a back portion, meansmounting the chart for rotation, backup means adjacent such backportion, means for straightening the indicia-bearing portion of thechart by engaging such front portion and moving such back portionagainst the backup means, and means for sensing the indicia on suchstraightened portion of the chart.

Prior charts for weighing scales were usually printed by an oifsetprinting process before etching. Certain disadvantages are inherent inthis method because the rubber roller which transfers the image of theindicia from the master to the chart tends to produce a slightly ovalreproduction even though the master is perfectly circular. If the chartsare to be used in ordinary printing scales so that the indicia on thecharts must serve as type, or if the charts are to be used in connectionwith the chart reading device embodying the invention, which convertsinformation from the charts into a form suitable for operatingindicating or recording devices, so that raised graduations suitable forsensing by such reading device must be on the charts, the charts may beproduced by a photoengraving process, i.e., the characters orgraduations are printed by an ordinary printing method to apply acoating unaffected by etching fluid and then the charts are etched. Theetching process, however, is not entirely satisfactory because theetching fluid tends to work back under the resistant printed on thesurface and, thus, produce a fuzzy edge on the characters orgraduations. This fuzzy edge tends to reproduce in the printed record ofthe weighings, in ordinary printing scales, so that the imprint on thetickets is not as sharp as may be desired, or the fuzzy edge, when usedin connection with the reading device embodying the invention, cannot besensed accurately by the reading devices feeler pins.

It is, accordingly, the principal object of this invention to provide animproved movable chart having relatively raised and depressed surfacessuitable for sensing by and in combination with reading means that sensethe chart axially and that converts such information as received fromthe condition responsive member into a form suitable for operatingindicating or recording devices.

Another object of the invention is to provide a reading device havingthe ability to read accurately a movably mounted chart that has anynonplane form such as a dish shape or an S shape.

Other objects and advantages will be apparent from the followingdescription in which reference is had to the accompanying drawings.

A preferred form of the invention is illustrated in the accompanyingdrawings.

In the drawings:

FIGURE I is an elevation of a weighing scale dial mechanism showing thelocation of the reading device and a recording device operated therebyas they are mounted on a weighing scale mechanism;

FIGURE 11 is a fragmentary schematic diagram to illustrate some of theoperating principles of the reading device;

FIGURE III is a diametric view of the permutation members and the drivemechanism therefor to show their cooperation with each other and withthe chart;

FIGURE IV is a horizontal section through the lower portion of theassembly of permutation members to show the cooperation between thepermutation members and the drive therefor;

FIGURE V is a plan view of one of the permutation members to show itsnotch pattern;

FIGURE VI is a fragmentary plan view of the notched portion of anotherpermutation member to show a second notch pattern;

FIGURE VII is a front elevation at reduced scale of the weighing scalechart suitable to be mechanically sensed axially by the permutationreading device;

FIGURE VIII is an enlarged fragment of the graduated portion of theweighing scale chart illustrated in FIGURE VII;

FIGURE IX is a section at enlarged scale taken substantially along theline IX-IX of FIGURE VIII to illustrate the shape of the individualchart graduations;

FIGURE X is a section at enlarged scale taken along the line XX ofFIGURE VIII to show the shape of locating notches employed to locate thechart prior to taking a reading;

FIGURE XI is a table showing the permutation code used for each of thegraduations of the chart;

FIGURE XII is an exploded view of locating mechanism employed to centerthe chart graduations prior to taking a reading so as to avoid anypossibility of selector pins of the permutation members failing toproperly engage the chart graduations;

FIGURE XIII is a plan view of the locating device;

FIGURE XIV is a vertical section along the line XIVXIV of FIGURE XIII;

FIGURE XV is a more or less schematic perspective view as seen from aposition along line XVXV of FIG- URE IV looking in the directionindicated by the arrows before the reading devices sensing cycle hasbegun; and

FIGURE XVI is a perspective view of the device which is illustrated inFIGURE XV after the sensing cycle has begun showing the locatingmechanism centering the chart graduations prior to taking .a reading.

These specific figures and the accompanying description are intendedmerely to illustrate the invention and not to impose limitations on itsscope.

For the purpose of illustration, the reading device is shown inconnection with an ordinary dial type weighing scale. Such a scalecomprises a dial housing 2 that contains automatic load counterbalancingand indicating mechanism which may include an annular chart 2 that isrotated through increments of angle that are proportional to incrementsof weight applied to the scale. The chart housing it is mounted on thetop of a scale column 3 of which only the top portion is shown in FIGURE1.

The chart reading mechanism is contained within a housing 4 attached tothe dial housing 1 and is connected through a conduit 5 to a printer orother utilization device 6 which is to be operated according to thescale readings. The chart 2 has on its face a series of graduations 7that are visible through a magnifying lens 8 to provide visualindications of the load on the scale. The face of the chart 2 is alsoprovided with molded graduations or indicia 9 consisting of relativelyraised and depressed surfaces, as shown in greater detail in FIGURESVlii, IX and X, constituting the indicia that are sensed by the readingdevice contained within the housing 4.

FTGURE 11 shows in schematic form one of each of the essential elementsof the reading device while FIG- URE ill shows a complete assembly ofthe sensing and selecting portions of the reading device. Referringfirst to FiuURE ii, a reading of the chart 2 is taken by first advancinga series of sensing pins 110, one of which is shown, by spring-urgedrotation of permutation disks 1i to positions at which they are arrestedby engagement of the sensing pins in with the indicia 9 of the chart 2.Prior to the engagement of the sensing pins with the indicia a cam 12forming part of a drive member 13, through engagement with a roller 14,drives a resiliently mounted finger 15 toward the chart until its tip 16engages a row of raised teeth 17 and comes to rest either betweenadjacent teeth or on the crest of a tooth. Continued motion of the camfollower lid turns a rubber tired wheel 18 in a direction tending tomove the chart 2 so that the tip of the finger 16, if it had lodged on acrest of a tooth i7, is permitted to enter the space between two of theteeth and thus locate the chart 2. If the tip 1-? were already engagedin a space between two of the teeth 17, the wheel slips leaving thechart 2 in position with the corresponding graduation centered in thepath of the sensing pins 1%. Thus, the pins it either enter squarelyinto the spaces between indieia 9 or onto the crests depending upon thecoding of the indicia for that particular graduation.

After the permutation disks 11 are retracted without disturbing theirrelative positions as determined by the engagement of the sensing pins10 with the chart 2, search pawls 20, one for each decade, carried onpawl arms 21 and each cooperating with four of the permutation disks 11search notches 22 in the peripheries of the permutation disks 11. Aseach pawl finds aligned notches in its set of four permutation disks 11it stops the pawl carrier in a position corresponding to the particulargraduation of the chart being sensed. The stopped pawl carriers, throughtheir connections through cables 23, position a reading device orindicating device according to the sensed graduation.

The movement of the drive member 13 is produced and controlled by aconnecting rod 24 and crank 25 driven by a motor 26 equipped withcontrols to cause it to drive the crank 25 through one revolution foreach start signal.

The sequence of steps in thus taking a reading from the chart 2 is toenergize the motor such that it turns the crank 25 and thus oscillatesthe drive member 13. This oscillation first drives the cam follower iland finger 15 toward the chart to locate it with a graduation accuratelyin line with the sensing pins 10. During the oscillation of the drivemember 13 the permutation disks 11, four for each decade, are driven sothat their respective pins 16) engage the chart and then are retractedwithout disturbing their relative positions with respect to each otherto a locking position at which they are held while the searching pawls20, one for each group of four permutation disks or one for each decade,search the peripheries of the permutation disks 11 for the alignednotches. Upon finding the aligned notches the pawls stop the respectivepawl carriers 21 in proper indicating positions.

The whole combination or assembly of permutation disks and drive membersis shown in greater detail in FTGURE iii. The complete stack up ofpermutation disks 11 for a four place number includes sixteen of thepermutation disks 11, four pawl carriers 21, and enough spacers 27 toseparate each of the permutation disks 11 from its neighbor for from apawl carrier 21 as the case may be. Thus, sixteen permutation disks 11and four pawl carriers 21 plus an extra spacer at the top of the stackrequires a total of twenty-one spacers 27. Each of the spacers isprovided with bifurcated ears 28 and 29 adapted to slip into notches insupport rods of a frame with the rods holding the spacers in alignmentand in spaced relation. Each of the spacers also has an inwardlydirected notch 30 on the side facing the chart that terminates in anarrow slot 31 adapted to fit into corresponding groove cut in an axle32 on which the permutation disks 11 and pawl carriers 21 are journaled.Thus, each of the spacers 27 has a three point support so as to separatethe permutation disks and still allow them to move easily as may berequired in sensing the chart or in carrying the pawls '20 along thenotched peripheries of the permutation disks 11.

The sensing pins 10 each has a pointed end 33 that is sharp enough toenter the spaces between alternate gradutions and yet blunt enough toavoid cutting the chart material and has its other end curled into acircular loop 34 that is a close sliding fit in a hole cut in theconnected permutation disk 11 so that the pin moves in the manner of aflat ball and socket joint. This particular construction keeps thethickness of the permutation disk and pin a minimum so that it may fitbetween closely spaced adjacent spacers 27.

The permutation disks 11 are continually urged in a direction tending todrive the sensing pins 11} against the chart by spring teeth 35 of acomb spring 36 that is carried on a common pawl bail 37. The ends of thespring teeth 35 engage notches 38 in the permutation disks. Movement ofthe permutation disks 11 under the influence of the springs 35 islimited by a common pawl 40 that is carried in the bail 37 and arrangedto selectively engage either of two notches 41 or 42 of each permutationdisk 11 and lock it in position when the pawl engages hooklike portions43 (FIGURES IV) of the bifurcated cars 29 as the bail 37 is urgedcounterclockwise, as seen in FIGURES III and IV, by a return spring 44attached to its lower end. The common pawl 46 is held seated in pivotnotches 45 of the bail 37 by a plurality of small spring 46 forming partof the comb spring 36 and attached to the bail 37. The pawl 40 is urgedinto engagement with the notches 4-1 or 42 by a light spring 47 alsoattached to the bail 37.

operation, as the drive member 13 is swept clockwise as seen in FIGURESiii or TV it collects the pawl carriers 21 from their previous positionsand finally engages an upwardly directed stud 43 carried in an upper armof the bail 37 so as to drive the baii clockwise through a smalldistance against the tension of the return spring 44. During the initialmovement of the bail 37 it and the permutation disks it move as a unitsince the disks a held between the spring teeth en the notches .29 andthe pawl engaging the notches 41 or As the sensing pins iii engage thechart 2 and drive it against aces,

a backup roller 50 the motion of the permutation disks 11 is arrested.The spring teeth yield as the bail 37 continues and the pawl 40 leavesthe notches 4-1 or 4-2 and slides'part way along the smooth periphery ofthe per-mutation disks ill between the notches 41 and 38. This motion isjust far enough to make sure that the common pawl 46} is out of thenotches. On the return motion of the drive member 13, the spring 44pulls the common pawl bail 37 counterclockwise so that the common pawl46 may enter the aligned ones of the notches 41 or 42 in each of thepermutation disks according to whether the disk had been advanced by itspin finding a low spot in the chart or whether it had been arrested inthe first position with the pin on the crest of a graduation. Thecontinued motion with the common pawl 49 engaged in the permutationdisks drives the disks in retracting motion until the common pawl 49seats behind the hooklike portions 43 of the spacer cars 29. At thispoint the motion of the common pawl bail 37 is arrested and thepermutation disks 11 are all locked in position.

Continuing motion of the drive member 13 allows the pawl carriers 21 tofollow as urged by their drive spring 52, one of which is shown inFIGURE IV connected to its cable 23. The pawl carriers 21 move untiltheir pawls 20 find aligned notches in a particular combination ofpermutation disks with which they cooperate. It is to be noted that theposition of the aligned notch may vary according to the relativepositions of the group of disks cooperating with each pawl.

The sensing pins in adjacent the chart 2 are guided in slots 54 of aguide plate 55 that is attached to a frame support 56 that serves as thespacing support for the bifurcated ears 28 of the spacers 27. The slots54 are just wide enough to admit the pins and, thus, accurately guidethem closely adjacent the chart 2. As indicated in FIGURE IV, the guideplate 55 is adjustable relative to the frame support rod 56 and iscontrolled by an adjusting screw 57 that Works in opposition to thecommon pawl bail return spring 4-4.

The return springs 52 may be the springs in the printer mechanism tomaintain tension on the cables 23 or if a commutator, not shown in thedrawings, be attached to the pawl carriers 21 the spring 52 may bereturned to the frame mechanism merely to apply tension to the cable 23and do no other useful work. If a printer, as indicated in FIGURE I, isenclosed in the housing 6 the cables 23 are run through the conduit 5from the selector mechanism in the housing 4.

Referring to FIGURE IV, each cable 23 is passed over an arouate surfaceor periphery 5% of its pawl carrier 21 and its end is anchored in a hole5% drilled through the pawl carrier. The spacers 27 hold the cable 23from slipping off sideways. The radius of the arcuate surface 53 withrespect to the axle 32 on which the pawl carrier is journaled isselected according to the desired travel of the cable 23 for eachincrement of indication and the spacing of the notches 2-2 whichdetermine the angular travel of the pawl carrier.

The permutation disks 11 are made with either of two notch patterns andthe selector pawls 2d are arranged with one of its teeth advanced twonotch spaces ahead of the other tooth. By thus varying the spacing ofthe pawl teeth and providing the two different patterns for the selectordisks it is possible to secure at least eleven different combinations toprovide different stopping points for the pawl 20. FIGURES V and VI showthe two notch combinations for the permutation disks 11. In the typeshOWn in FIGURE V the notched periphery is divided into twenty-threeequal spaces with notches appearing in the first, third, fourth, sixth,ninth, tenth, twelfth, fifteenth, seventeenth, eighteenth, twentieth,and twenty-third spaces counting from left to right. Likewise, thepermutation pattern shown in FIGURE VI has notches appearing in thefirst, second, fifth, sixth, ninth, tenth, thirteenth, fourteenth,seventeenth, nineteenth, twenty-first,

. 6 and twenty-third spaces. These particular notch combinations used inpairs with the offset pawl teeth operate according to the code set forthin FIGURE XI. This code is used in determining the location of theraised and depressed indicia for each of the graduations on the chart 2to be sensed.

As shown in FIGURE VII, the chart 2 is an annular member carried on aspider 6t) and having rows of graduations 61 on its marginal area. Inorder to allow for expansion and contraction of the chart 2 and thespider 66 relative to each other due to temperature changes, the spider60 is slotted radially at 60a to loosely receive a rivet 61a, hasopenings 6% which loosely receive rivets 61b, and has an aperture 600which fits snugly about rivet 610. The rivets hold the chart 2 and thespider 69 together, the heads of the rivets being sheared off and thebodies of the rivets shown in section in FIGURE VII for clarity ofillustration. The graduations or indicia are preferably molded in theface of the chart in the same manner as phonograph records are made witha plastic or other moldable layer 62 mounted on a metallic backing plate63 and the graduations being formed in the plastic layer. Thearrangement of graduations for a first fragment of the chart isillustrated in FIGURE VIII. This fragment, starting with the zeroindicia of the chart, shows only those graduations in the units orlowest order decade and the row of teeth 17 for locating the chart. Theteeth 17 along the marginal area of the chart cooperate With thelocating finger 15 and have cross sections as shown in FIGURE X whereineach of the teeth is shown substantially as a conventional rack tool.The tip 16 of the locating finger 15 is formed as a mating tooth so asto seat firmly in the spaces between the teeth 17.

The indicia 9 with which the sensing pins 10 cooperate are of generallysimilar shape except for being formed of heavier section inasmuch as thelocating pins do not have to fit into the spaces between teeth that arelocated on adjacent graduations. The chart section shown in FIG- UREVIII, as was mentioned, includes that portion starting at the zerograduation which is shown at the righthand edge. Inasmuch as there areno significant figures to the left of the zero when indicating the zerograduation it is desirable that the indicator show or the printer printa blank at this position. Therefore, the first graduation carries onlythe single raised portion in the bottom row or D row which, according tothe chart shown in FIGURE XI, gives a blank for the output indication.The permutation disk combination for this graduation causes the alignednotch to appear at the end of the travel of the pawls 20 or at the lastpossible position at which an aligned notch may be formed. If an erroris made such that the pawl does not find the aligned notch itovertravels and the printer indicates such overtravel by printing somedistinctive symbol in place of a digit. The next graduation, a one, isindicated or denoted by a single raised indicia in the A row; likewisetwo is indicated by a sin le indicia in the C row; and the others followaccording to the chart. It should be noted that the raised indicia ofthe chart cause the corresponding permutation disk 11 to be advancedcounterclockwise one space as seen in FIGURES III or IV.

Other chart combinations may be employed besides the particular codeindicated. However, this particular code was selected in order that thenumber of different parts could be reduced. Thus, with the selected codetwo each of the permutation disks 11, shown in FIGURES V and VI, may beemployed in each decade in combination with the offset pawl 2d. If theoffset pawl were not employed then each of the four permutation diskscooperating for each decade would have to have its own combination ofnotches which would make four different parts to be stocked instead oftwo.

The plastic layer 62 is firmly attached to the metallic backing plate 63either by molding it in place or by adhesively applying it. The plasticlayer is then impressed in a molding operation with the rows orgraduations 631. The metallic backing plate 63 has appreciable thicknessand the moldable material 62 applied to its surface is of substantiallythe same thickness. The moldable material must be thick enough to takethe full depth of the impressions to be molded therein without havingthe dies of molds extend through to the metallic supporting member.

Freferably, the plastic layer 62 is molded into form and applied to thebacking plate 63 in one operation. Since heavy, rigid molds are requiredto mold the plastic layer these may be very accurately made so that themolded graduations 61 are precisely located around the chart and so thatthey are sharply formed, whereby the graduations are especially suitablefor accurate sensing by the feeler pins 1! The composite chart 2 ispreferably constructed from hard aluminum alloy so that it isdimensionally stable and able to stand the pressures in the mold. Tiemoldable material may be a soft metal alloy or any of the plastics whichwill adhesively bond to the aluminum. Ordinarily, a thermoplasticmaterial is employed so that the graduations will be very accuratelymolded by the application of heat and pressure. Thermoplastic materialsare preferred although thcrmosetting materials may also be used providedthat they will adhere to the aluminum or other metal used for the stablesupport. Suitable materials for coating the mold surface are availableto prevent adhesion of the molded layer of the chart to the mold.

The foregoing described construction for the chart 2 permits it to bemade at a small cost and with an accuracy that is limited only by theaccuracy of the master die that is used to construct the molds. Sincethis die may be very accurately machined and since there is no loss ofaccuracy in transferring from the master die to the mold die, it followsthat the molded charts are very accurate in dimension and will maintainthat dimensional accuracy in use.

Various modifications of construction and substitutions of material inthe chart 2 may be made without losing the advantages that are obtainedby using a high-strength dimensionally stable material as a backingsheet or support and molded onto a marginal area thereof a layer ofmoldable material only sufficiently thick to receive the impressions ofgraduations or indicia to be placed thereon.

The chart locating mechanism is illustrated in greater detail in FIGURESXII, XIII and XIV. Referring to FIGURE XII, the cam follower 14 ismounted on the end of a forearm 65 that also carries, as a rigid partthereof, at its elbow end the drive wheel 18 that engages the chart tourge it forward so as to move any tooth 17 falling below the finger tip16 out of the way and allow the tip 16 of the finger 15 to fall into thespace between adjacent teeth 17. The arm 65 is pivotally connectedthrough an elbow joint at the. axis of the wheel is to a second arm 66which in turn is pivoted on and, by a spring not shown, is continuallyurged clockwise about a pin 67 fixed in the framework of the scale. Aspring 68 at the joint or elbow at the wheel It; urges the forearm 65clockwise with respect to the second arm 66 so that the wheel bearsagainst the chart 2 before the elbow joint starts to turn. The springurged movement of the forearm 65 relative to the second arm 66 islimited by a down turned ear 6) on the tail end of the forearm 65 thatengages the front surface of the lower arm 66. Normally, the spring 68rotates the fore.- arm 65 to maintain the ear in engagement with thelower arm. However, when the mechanism is pushed toward the chart by thecam pushing on the cam roller 14 the lateral motion of the wheel 13 isarrested and the cam force against the cam follower 14- then rotates thearm 65 around its connection with the lower arm 66 thus producing therelative rotation of the wheel 18.

The finger 15 with its tip 16 is carried on the pin 67 and is urgedtoward the chart by a spring 70 acting between the lower arm 66 and thefinger 15. The forward moveeaaso ment of the finger 15 is limited by astop 71 erected from the rear portion of the lower arm 66 in position toengage the chart side of the finger 15.

FIGURE XiV is a section taken through the elbow joint between the arms65 and 66 and shows a rubber tire '72 mounted on the wheel 18 so as toincrease the tractive effort of the wheel on the chart.

In the operation of this mechanism the spring 68 is made stiff enough sothat when the wheel 18 engages the chart it pushes the chart backagainst the backup roller 56 before the spring 68 yields and permits thearm 65 to turn relative to the arm 66. This insures that sufficientforce is exerted against the chart to cause it to move even though thetip 16 of the finger 15 should be partially caught on the corner of thecrest of a tooth. It is necessary that sufiicient force be exerted atthe time so that the tip of the finger 15 will slide across the crest ofa tooth 17 and firmly engage in the valley against the side of the nexttooth 17.

The metallic backing plate 63 of the chart 2 is pro-spun to a nonplane,dished form with the layer of moldable material 6. molded on theconcave, front side as illustrated in FIGURE XV. The nonplane form isimportant because it has been found that a flat chart of the diameterand thinness needed warps and acts like the bottom of an oil can duringtemperatures changes. The chart must be made thin to reduce the inertiaand for good flexibility so that good contact is made between the backof the chart and the backup roller 50 when the chart is sensed by thereading device. Such good contact is enhanced by the fact that the chartis molded on its concave side, and is very important in order that thetotal movement of all of the sensing pins 10 may be determinate and maybe made with a minimum of effort. The chart may have any nonplane formsuch as an S shape, the reading device having the ability to readaccurately a chart that is warped into any nonplane form. The chart ismade from thin, light-Weight material to reduce the inertia, but whichwarps easily, and wobbles back and forth as it passes by the sensingpins. Nevertheless, the reading device by straightening theindicia-bearing portion of the chart is able to read the chartaccurately.

The concave chart 2., in its position shown in FIGURE XV, is free torotate through increments of angle that are proportional to incrementsof weight applied to the scale, the chart reading mechanism being shownin its idle stage, i.e., the rubber tired wheel 18 and the finger tip 16of the locating mechanism and the sensing pins 10 are illustrated intheir normal positions prior to a sensin cycle. a

FIGURE XVI is an illustration of the relative positions of the elementsduring the first stage in the sensing cycle. In the first stage, whichis prior to the engagement of the sensing pins 16 with the indicia 9,the finger tip 16 is driven toward the chart 2 until it engages the rowof raised teeth 17 and comes to rest either between adjacent teeth 17 oron the crest of a tooth 17. Continued motion of the cam follower l l(FIGURES X11 and XIII) turns the rubber tired wheel 13 in a directiontending to move the chart 2 so that the finger tip 16, if it had lodgedon a crest of a tooth 17, is permitted to enter the space between two ofthe teeth and, thus, locate the chart 2. If the tip 1.6 were alreadyengaged in a space between two of the teeth 17, the wheel slips leavingthe chart 2 in position with the corresponding graduation centered inthe path of the sensing pins it As shown in FIGURE XVI, the rubber tiredwheel 1% is pushing the concave chart 2 back against the roller 5% andthe tip 16 is engaged in a space between two of the teeth 17. In thenext stage in the sensing cycle, the pins 10 are advanced to read thealready pushed back chart 2.

The flexibility of the chart 2 makes possible the good contact betweenthe chart and the backup roller 50 which is illustrated in FIGURE XVI.Such prior contact of the chart and the roller leaves little work forthe sensing pins 9 10 to do, the upper ones of the pins 10 finishing thetask of completely pushing the chart back.

The construction and form of the chart permits the use of extremelysmall graduations on the chart and, hence, a large number of suchgraduations without requiring correspondingly accurate alignment of thechart as a Whole. Thus, the chart may run out or wobble a distanceseveral times the depth of the chart graduations without affecting theaccuracy of the readings. A twisted, wobbling chart which is pushed backagainst a stop and then sensed is believed to be unknown in the priorart.

Various modifications in the structure may be made without losing theadvantages of the structure disclosed or departing from the scope of theinvention.

Having described the invention, I claim:

1. In a mechanical chant reading device, in combination, a flexibleannular chart of dished form having a concave portion carrying raisedindicia, means connected to said chart for mounting said chart forrotation, backup means positioned radially adjacent the convex side ofsaid chart, means for straightening the indicia-bearing portion of thechart by moving such convex portion against the backup means, and meansfor sensing the indicia on such straightened concave portion of thechart.

2. A mechanical chart reading device according to claim 1 wherein theraised indicia are selected according to a binary code.

3. A mechanical chart reading device according to claim 1 wherein thechart has a composite structure.

4. In a mechanical chart reading device, in combination, a flexibleannular chart of nonplane form having a front portion carrying raisedindicia and a back portion, means mounting the chart for rotation,backup means adjacent such back portion, means for straightening theindiciabearing portion of the chart by engaging such front portion andmoving such back portion against the backup means, and means for sensingthe indicia on such straightened portion of the chart.

5. A mechanical chart reading device according to claim 4 wherein theraised indicia are selected according to a binary code.

6. A mechanical chart reading device according to claim 4 wherein thechart has a composite structure.

References Cited in the file of this patent UNITED STATES PATENTS385,887 Tainter July 10, 1888 1,496,258 Ewing June 3, 1924 1,950,187Mansel Mar. 6, 1934 2,008,092 Biber July 16, 1935 2,169,213 BackdahlAug. 15, 1939 2,308,927 Maul Jan. 19, 1943 2,374,790 Terry May 1, 19452,453,239 Luhn Nov. 9, 1948 2,678,895 Belar May 18, 1954 2,792,275Drillick May 14, 1957

